Load cell closed loop control for rotary ultrasonic bonding apparatus

ABSTRACT

Apparatus and methods for effecting ultrasonic bonds in sequentially advancing workpiece segments, in a nip defined by a rotary ultrasonic horn and rotary anvil roll. The ultrasonic bonding apparatus comprises support structure comprising anvil support apparatus and horn support apparatus. A closed loop control apparatus is connected to one or both of the anvil support apparatus and horn support apparatus. The closed loop control apparatus comprises a programmable logic controller, a load cell, and an adjustor. Information output from the load cell triggers the closed loop control apparatus through the programmable logic computer and the adjustor to move one or both of the anvil support apparatus and horn support apparatus toward or away from the other in dynamic response to the information output from the load cell, thereby regulating pressure in the nip with ongoing real-time adjustments to distance between the anvil support apparatus and the horn support apparatus.

BACKGROUND

The present invention relates to apparatus and methods for creatingultrasonic bonds in a web or webs, and/or in discrete workpiecesegments, optionally in combination with a web or webs, using ultrasonicbonding apparatus. The invention more particularly concerns apparatusand methods for ultrasonically bonding a web or webs, and/or discreteworkpiece segments, optionally in combination with a web or webs, usinga rotary ultrasonic horn and a rotary anvil.

Bond strength, where a rotary ultrasonic horn and a rotary anvil areused to bond webs, or discrete workpiece segments is dependent on avariety of factors including horn frequency, horn amplitude, dwell timein the nip, bond pattern, and nip loading. More specifically, theconsistency and quality of the bond when using such rotary bondingtechniques is significantly dependent on the consistency of the forceexerted on the web by the combination of the anvil roll and the rotaryultrasonic horn; the time during which the web is being pressed in theconstrictive nip which is dependent in part on the operating speed atthe nip; and the nature of the materials being bonded. The consistencyand quality of the bonds are also dependent on the frequency andamplitude of the vibrations of the ultrasonic horn.

Consistency and quality of bonds when using conventional rotaryultrasonic bonding methods and apparatus have been particularly variablewhere the desired bond pattern is intermittently imposed on the materialpassing through the bonding nip because the nip pressures inherentlychange in concert with the intermittent nature of the bonding operation.

When nip loading is excessive, so much energy may be applied to thematerials being bonded as to burn through or otherwise excessivelysoften the materials being bonded, as well as to apply so much pressureto the softened materials that the bonds so formed may be weak, and/ormay be uncomfortably harsh to the touch of a wearer's skin. In thealternative, excessive loading can physically damage, as by tearing, thematerial being bonded. Additionally, excessive loading can increase wearor coining and thus damage the ultrasonic horn.

In the past, control of the nip force has evolved from constant force tofixed interference. More specifically, early practice in the art ofultrasonic bonding was to force an anvil against a horn with a fixed,defined load. The anvil rode on the horn much like a train wheel runs ona rail. The force applied was substantially constant regardless of thepresence or absence of material in the nip. The constant force of thefixed load design at high force levels tended to cause rapid horn wear.

The next step in the evolution of ultrasonic bonding was to load theanvil roll with high force against a fixed stop and to use the stop toestablish interference. In this design, the stop drew a relatively highfraction of the load until material entered the nip; at that point, thegreater interference caused by the material drew more of the load as thestop load diminished.

A need exists to develop apparatus and methods for loading a nip to aknown force rather than loading to a fixed interference. Similarly, aneed exists to develop apparatus and methods for loading a nip includingmeasuring and adjusting a nip load as a direct reading of force ratherthan as an inferred value from a change in interference.

It is another object of this invention to provide ultrasonic bondingapparatus and methods wherein the bonding apparatus transmits areal-time ongoing and dynamic signal output to apparatus which isdesigned and configured to automatically adjust nip loading toward aknown target load, without ongoing real-time human intervention.

It is yet another object of this invention to provide bonding apparatusand methods wherein a portion of the bonding apparatus can beautomatically raised or lowered in response to detected nip loadingoutput until the force applied to the respective portion of bondingapparatus results in desired ultrasonic bond-creating pressure in thenip.

SUMMARY

In a first family of embodiments, the invention comprehends ultrasonicbonding apparatus for creating ultrasonic bonds in sequentiallyadvancing workpiece segments, in a nip defined by a rotary ultrasonichorn mounted for rotation about a first axis, and a rotary anvil rollmounted for rotation about a second axis substantially aligned with thefirst axis. The anvil roll comprises a width, a circumference, and abonding portion disposed about at least a portion of the circumference.The ultrasonic bonding apparatus comprises support structure comprisinganvil support apparatus and the horn support apparatus. The anvilsupport apparatus is connected to the anvil roll, and horn supportapparatus is connected to the ultrasonic horn. The support structuresupports the bonding apparatus from an underlying support. The anvilsupport apparatus comprises an anvil moving assembly for moving theanvil roll into contact with the ultrasonic horn, and for moving theanvil roll out of contact with the ultrasonic horn. Closed loop controlapparatus is connected to one of the anvil support apparatus and thehorn support apparatus. The closed loop control apparatus comprises aprogrammable logic controller, a load cell, and an adjustor. Theultrasonic horn and the anvil roll collectively are mounted andconfigured such that the ultrasonic horn and the anvil roll can bebrought together to define the nip therebetween, wherein the anvil rolland the ultrasonic horn can rotate in common with movement of workpiecesegments through the nip. Information output from the load cell triggersthe closed loop control apparatus through the programmable logiccomputer and the adjustor to move the one of the anvil support apparatusand the horn support apparatus toward and away from the other of theanvil support apparatus and the horn support apparatus in automatic anddynamic response to the information output from the load cell, therebyregulating pressure in the nip with ongoing real-time adjustments todistance between the anvil support apparatus and the horn supportapparatus without real-time operator intervention.

In preferred embodiments, the load cell is arranged and configured tomeasure representative nip loads, thereby to define forces generatedbetween the ultrasonic horn and the anvil roll.

In some embodiments, the adjustor comprises a servo motor.

In some embodiments, the invention comprises a load cell conditionerconnected to the load cell. The load cell conditioner functions toamplify output from the load cell.

Preferred embodiments can include a back-up roll juxtaposed adjacent theultrasonic horn, opposite the anvil roll, wherein the back-up rollengages an outer surface of the ultrasonic horn at an engagement locusin alignment with a line extending through extensions of the first andsecond axes.

In some embodiments, the invention includes a second adjustor mountedand configured for adjusting a height of the back-up roll, and thusgenerally defining a limit to movement of the ultrasonic horn away fromthe anvil roll.

In some embodiments, the closed loop control apparatus is connected tothe horn support apparatus.

In other embodiments, the closed loop control apparatus is connected tothe anvil support apparatus.

In some embodiments, the anvil moving assembly defines a limit to travelof the anvil support apparatus away from the horn support apparatus,thus defining a limitation to withdrawal of the anvil roll from the nip.

In some embodiments, the invention includes first and second supportrolls releasably supporting opposing sides of an outer surface of theultrasonic horn. Axes of the first and second support rolls can bepositioned lower than the axis of the ultrasonic horn, whereby urgingthe first and second support rolls inwardly against the outer surface ofthe ultrasonic horn lifts the ultrasonic horn upwardly against theback-up roll.

In some embodiments, the invention includes drawing apparatus, capableof drawing the workpiece segments through the bonding apparatus, acrossthe anvil roll, and thus through the nip defined between the anvil rolland the ultrasonic horn, at a threading speed of at least about 40 feetper minute, preferably at a speed of at least about 600 feet per minute,more preferably at a speed of at least about 1000 feet per minute.

In preferred embodiments, the support structure is sufficiently rigidthat the ultrasonic horn and the anvil roll can be brought together withdeflection levels of the horn support apparatus and the anvil supportapparatus, in combination, being no more than about 0.003 inch incombination with defining sufficient nip pressure to develop ultrasonicbonds in the workpiece segments passing through the nip. Deflection iscalculated using the formula, d=(Fl³)/3EI, wherein “F” represents theforce expressed in the nip, “I” represents the length of the supportstructure, “E” represents the modulus of elasticity of the materialcomprising the support structure, and “I” represents the moment ofinertia for the cross-sectional area of the support structure. Themoment of inertia for a support structure having a solid rectangularcross-section is calculated using the formula, I=(bh³)/12, wherein “b”represents the length of the base of the support structure, and “h”represents the height of the support structure. The moment of inertiafor a support structure having a solid circular cross-section iscalculated using the formula, I=(nd⁴)/64, wherein “d” represents thediameter the circular support structure.

In a second family of embodiments, the invention comprehends closed loopcontrol apparatus for managing pressure generated in a nip. The nip isdefined between a rotary ultrasonic horn mounted for rotation about afirst axis and an anvil roll mounted for rotation about a second axis,substantially aligned with the first axis. The anvil roll is mounted tosupport structure by anvil support apparatus, and the ultrasonic horn ismounted to the support structure by horn support apparatus. The closedloop control apparatus comprises a load cell, a programmable logiccontroller, and an adjustor. The load cell is connected to one of theanvil support apparatus and the horn support apparatus. The load cellquantifies force representative of pressure being generated in the nip.The programmable logic controller is connected to the load cell and tothe adjustor, for communication with the load cell and the adjustor. Theadjustor is mounted in adjusting relationship with the anvil supportapparatus.

In preferred embodiments, the closed loop control apparatus furthercomprises a strain gauge isolated transmitter converting force appliedon the load cell into signal output.

The load cell preferably functions to transmit the signal output to theprogrammable logic controller.

In some embodiments, the anvil support apparatus can be raised orlowered by the adjustor in response to output of the load cell and theprogrammable logic controller until force applied to the anvil supportapparatus results in desired ultrasonic bond-creating pressure in thenip.

The horn is preferably mounted from a horn support apparatus having afirst end portion mounted to the support structure, and a second endportion remote from the first end portion, and disposed on a horn movingassembly.

In some embodiments, the closed loop control apparatus is operativelyconnected to the anvil support apparatus, and a second closed loopcontrol apparatus is connected to the horn moving assembly, therebyproviding a second control for managing pressure in the nip. The secondclosed loop control apparatus comprises a second adjustor mounted inadjusting relationship with the horn moving assembly, and a second loadcell connected to one of the horn moving assembly and the secondadjustor, and outputting information to a suitable programmable logiccontroller.

In a third family of embodiments, the invention comprehends a method ofcreating ultrasonic bonds in sequentially advancing workpiece segments.The method comprises passing the workpiece segments through a nip,activating ultrasonic energy in an ultrasonic horn at the nip, andthereby creating ultrasonic energy in workpiece segments passing throughthe nip. The nip is defined by a support structure comprising anvilsupport apparatus, horn support apparatus, and closed loop controlapparatus. The anvil support apparatus supports an anvil roll mountedfor rotation about a first axis. The horn support apparatus is connectedto and supports a rotary ultrasonic horn mounted for rotation about asecond axis, substantially aligned with the first axis. The anvilsupport apparatus comprises an anvil moving assembly for moving theanvil roll into contact with the ultrasonic horn, and for moving theanvil roll out of contact with the ultrasonic horn. The closed loopcontrol apparatus is connected to one of the anvil support apparatus andthe horn support apparatus, and comprises a programmable logiccontroller, a load cell, and an adjustor. The method also includesrotating the ultrasonic horn and the anvil roll in common with movementof the workpiece segments through the nip, thereby applying pressure tothe workpiece segments at the nip and correspondingly creatingultrasonic bonds in the workpiece segments passing through the nip.

In preferred embodiments, the method includes sensing nip loads usingthe load cell, the nip loads representing forces expressed between theultrasonic horn and the anvil roll at the nip.

In some embodiments, the method includes employing the horn supportapparatus and the anvil support apparatus, collectively, thereby todefine a set-point target nip pressure of at least about 400 pounds perinch width of the nip, the nip having a width defined between theultrasonic horn and the anvil roll.

In some embodiments, the method includes initiating adjustment to theanvil moving assembly when nip load deviates from a target nip load byat least about 10 pounds per inch width of the nip.

In some embodiments, the method includes adjusting the anvil movingassembly when loading in the nip corresponding to a bonding portion ofthe anvil roll varies by more than about 10 pounds per inch width of thenip from the target nip loading.

In some embodiments, the method includes connecting the closed loopcontrol apparatus to the horn support apparatus.

In other embodiments, the method includes connecting the closed loopcontrol apparatus to the anvil support apparatus. In yet otherembodiments, the method includes managing pressure in the nip byemploying a second closed loop control apparatus connected to the hornsupport apparatus in combination with the closed loop control which isconnected to the anvil support apparatus.

In preferred embodiments, the method includes processing informationoutput from the load cell in the programmable logic controller andcorrespondingly raising and lowering one or both of the anvil movingassembly or the horn support apparatus, thereby regulating the pressurein the nip.

Preferred embodiments of the method comprise applying first and secondsupport rolls to sides of the ultrasonic horn and moving the ultrasonichorn into engagement with a back-up roll aligned with extensions of thefirst and second axes such that the first and second support rolls, incombination with the back-up roll, define a fixed location of operationof the ultrasonic horn.

In preferred embodiments, the bringing of the anvil roll and theultrasonic horn together comprises lifting the anvil roll, thereby tobring the anvil roll into engaging relationship with the ultrasonichorn.

Preferred embodiments generally include limiting downward movement ofthe anvil moving assembly and thereby preventing disengagement of driveapparatus which transmits drive power between the anvil supportapparatus and the horn support apparatus.

In some embodiments, the method includes adjusting height of the back-uproll and thereby controlling the location of operation of the ultrasonichorn.

In some embodiments, the method also comprises releasing the supportrolls, causing the horn to drop out of engagement with the back-up roll,and subsequently re-engaging the support rolls with the ultrasonic horn,and thus bringing the ultrasonic horn back into engagement with theback-up roll, and thereby returning the ultrasonic horn to the definedlocation of operation of the ultrasonic horn.

In preferred embodiments, the method includes using the load cell tomeasure, and to dynamically manage, nip loads expressed in the nip, inreal time.

Preferred embodiments of the method also generally include urging theanvil support apparatus, and the horn support apparatus together,wherein the anvil support apparatus and the horn support apparatus,collectively, are sufficiently rigid that the ultrasonic horn and theanvil roll can be brought together with deflection levels of the hornsupport apparatus and the anvil support apparatus being no more thanabout 0.003 inch in combination with defining sufficient nip pressure todevelop ultrasonic bonds in the workpiece segments passing through thenip.

In a fourth family of embodiments, the invention comprehends a method ofmanaging and regulating pressure generated in a nip. The nip is definedbetween a rotary ultrasonic horn mounted on horn support apparatus, andan anvil roll mounted on anvil support apparatus. The anvil supportapparatus is mounted to a support structure, and defines an adjustableanvil moving assembly. The horn is mounted in general alignment with theanvil roll to define the nip therebetween such that outer workingsurfaces of the ultrasonic horn and the anvil roll are generally definedin a common surface at the nip. The method comprises employing a loadcell connected to one of the horn support apparatus and the anvilsupport apparatus, and thereby receiving and quantifying forcerepresentative of force expressed between the ultrasonic horn and theanvil roll at the nip. The method also comprises converting the forceapplied at the load cell into a communications signal output. The methodadditionally comprises transmitting the communications signal output toa programmable logic controller programmed to activate an adjustor. Themethod further comprises employing the adjustor to raise or lower therespective anvil support apparatus or horn support apparatus so as toadjust the force being expressed between the anvil roll and theultrasonic horn at the nip to a desired bond-creating pressure.

In some embodiments, the method includes employing a target nip pressureof at least about 400 pounds per inch width of the nip.

In preferred embodiments, the method includes initiating adjustment oflocation of the respective anvil support apparatus or horn supportapparatus when pressure in the nip deviates from the target nip pressureby a defined number of pounds per inch width of the nip.

Preferred embodiments generally include adjusting the location of therespective anvil support apparatus or horn support apparatus whenpressure in the nip corresponding to a bonding portion of the anvil rolldeviates from the target nip pressure by a defined number of pounds suchas about 10 pounds per inch width of the nip.

In some embodiments, the method includes the horn support apparatushaving a first end portion fixed to the support structure, and a secondend portion remote from the first end portion, disposed on a horn movingassembly, the method including at least in part managing pressure in thenip by connecting closed loop control apparatus to the horn movingassembly.

In some embodiments, the method includes limiting downward movement ofthe anvil roll and thereby preventing disengagement of drive apparatuswhich transmits drive power between the anvil roll and the ultrasonichorn.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an overall representative pictorial view of bondingapparatus of the invention, including ultrasonic horn and supportapparatus, anvil and support apparatus, and a frame supporting both thehorn and the anvil.

FIG. 2 shows a more detailed representative pictorial view of ultrasonichorn support apparatus illustrated in FIG. 1.

FIG. 3 shows a more detailed representative pictorial view of anvilsupport apparatus illustrated in FIG. 1.

FIG. 3A shows a pictorial relational view of the gears of the anvilsupport apparatus illustrated in FIG. 3.

FIG. 4 shows a front elevation view of a representative ultrasonic hornsupport apparatus illustrated in FIG. 1, showing first and second websprogressing through a nip defined between an ultrasonic horn and acooperating anvil.

FIG. 5 shows a representative side elevation view of the apparatusillustrated in FIG. 4.

FIG. 6 shows a representative example of an anvil roll useful in theinvention, including first and second bonding regions.

FIG. 6A shows a representative side elevation view of a compositesubstrate web which can be manufactured using apparatus and methods ofthe present invention.

FIG. 7 shows a side elevation representation of the anvil roll and thehorn, illustrating the inferred interference between the horn and anvil.

FIG. 8 shows a graph representing anvil stop force maintained in the nipthrough use of the closed loop control apparatus of the invention.

FIG. 9 shows a graph representing upper support wheel stop forcemaintained between the upper support wheel and the horn through use ofthe closed loop control apparatus of the invention.

The invention is not limited in its application to the details ofconstruction or the arrangement of the components set forth in thefollowing description or illustrated in the drawings. The invention iscapable of other embodiments or of being practiced or carried out invarious other ways. Also, it is to be understood that the terminologyand phraseology employed herein is for purpose of description andillustration and should not be regarded as limiting. Like referencenumerals are used to indicate like components.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention provides apparatus and methods for using a closed loopcontrol to measure nip loading in a rotary ultrasonic bonding nip, andto maintain a stable level of force in the nip while effectingultrasonic bonds on a continuously moving web or webs, and/or suchstream of workpiece segments. The apparatus and methods can be used inmaintaining substantially stable force levels while effecting an overallbonding pattern in workpiece segments, bonding second workplace segmentsto first workpiece segments, bonding discrete elements to a web or toworkpiece segments, and fashioning bonded regions spaced along one orboth the length and width of such web, webs, and/or workpiece segments.Apparatus and methods of the invention are particularly useful for e.g.ultrasonically bonding selected components into or in absorbent articlesusing rotary ultrasonic horns and cooperating rotary anvils. Theapparatus and methods can be used for bonding two workpiece segments toeach other to form a composite e.g. substrate material, and wherein thecomposite substrate material is optionally used subsequently in anabsorbent article such as, for example, a disposable diaper. The presentinvention is particularly useful in bonding one or more layers ofmaterial which preferably are made, at least in part, from thermoplasticpolymers.

In particular, apparatus and methods of the present invention can beused, for example, to form a waist band in a disposable diaper. Suchwaist band may be formed e.g. by bonding a waist band element to aworkpiece segment or by forming bonds internally within the workpiecesegment. In the alternative, apparatus and methods of the invention canbe used e.g. to attach mounting ears to a diaper, to attach a landingstrip to a diaper, or to form side seams on training pants. In addition,apparatus and methods of the present invention can be used inmanufacture of absorbent articles other than diapers, such as, forexample, training pants, feminine care products, incontinence garments,hospital gowns, and the like. All such alternative methods,configurations, and articles are contemplated as being within the scopeof the present invention. In light of the disclosure herein, other usesof the invention in connection with absorbent and other e.g. personalcare articles of manufacture will be obvious to those skilled in theart.

Where the invention is used in making waist bands, the heights of thewaist bands, e.g. as oriented on the body of a wearer, may be alignedalong the length of the workplace segment, such that bonding of thewaist band regions represents an intermittent and timed discontinuousbonding process, having non-bonded areas of the workpiece segmentdisposed between longitudinally spaced waist-bonded regions. So-bondedwaist band regions enhance fit and comfort of the diaper or otherpersonal care article about the waist of the wearer.

Referring to the drawings, FIG. 1 illustrates in semi-block format, thegeneral locations of the major elements and assemblies of apparatus ofthe invention. As illustrated in FIG. 1, bonding apparatus 10 of theinvention generally comprises a frame 12, anvil support apparatus 14supporting an anvil roll 16, and horn support apparatus 18 supporting anultrasonic horn 20. Together, horn 20 and anvil roll 16 form a bondingnip 22 which is illustratively bonding a workpiece segment 24 shown indashed outline passing through the nip. FIGS. 2 and 4 illustrate detailsof horn support apparatus 18. FIG. 3 illustrates details of anvilsupport apparatus 14.

Referring back to FIG. 1, frame 12 is fabricated from a rigid, stiffmaterial such as metal. Preferred metals include a variety of well knownstiff and rigid steel or cast iron compositions. Frame 12 includes abase plate 26, a rear plate 28 rigidly mounted to base plate 26 e.g. bywelding or bolting, and left and right side plates 30, 32, each beingrespectively rigidly mounted to both base plate 26 and rear plate 28e.g. as by welding or bolting. Side plates 30, 32 are each rigidlymounted to both base plate 26 and rear plate 28 whereby the so-definedframe 12 provides a support assembly suitably rigid for supporting theanvil support structure and the horn support structure, thereby toprovide an increased level of structural rigidity at nip 22 while alsoproviding for release from such rigidity to accommodate variations inthickness of the e.g. workpiece segment material passing through thenip.

Referring now to FIGS. 1 and 2, horn support apparatus 18 can be used incombination with anvil support apparatus 14 to develop bonds in acontinuously moving workpiece segment 24. In the alternative, anvilsupport apparatus 18 and horn support apparatus 14 can be used to bondtwo or more workpiece segments 24, 34 to each other as illustrated inFIG. 4 or to bond discrete elements to a workpiece segment or discreteelements to each other when at least one of the elements is alreadymounted or bonded to such workpiece segment. In any event, a continuousworkpiece segment is preferably involved in the bonding process, whetheras a support for elements being bonded to each other, as a continuouselement being bonded either to another continuous element or to discretespaced elements, or as a continuous element being bonded internallywithin its own structure. Workpiece segment 24 is continuously movingalong a substrate path 36 in the direction indicated by arrow 38.

Horn support apparatus 18 includes rotating ultrasonic horn 20 as abonding roll supported adjacent and above workpiece segment 24. Horn 20has an outer peripheral bonding surface 42 which contacts and acts uponworkpiece segment 24, and which rotates about a horn axis 44 in thedirection indicated by arrow 46. Rotatable anvil roll 16, part of anvilsupport apparatus 14, is located adjacent horn 20. Anvil roll 16 isconfigured to rotate about anvil axis 50 in the direction indicated byarrow 52 associated therewith to press workpiece segment 24 againstbonding surface 42 of horn 20, thereby creating bonds at workpiecesegment 24.

In the embodiments illustrated in FIGS. 1, 2. 4, and 5, outer peripheralbonding surface 42 is contacted and supported by back-up roll 54 andfirst and second support rolls 56A and 56B. In the. illustratedexamples, rolls 54, 56A, and 56B are spaced at regular intervals aboutouter peripheral bonding surface 42 of horn 20 so as to maintain thehorn in a substantially fixed position while the horn is being used toform ultrasonic bonds.

Horn support apparatus 18 includes horn support assembly 58 which isconfigured to bring support rolls 56A and 56B into contact with outerbonding surface 42 of horn 20, and raise horn 20 into contact with theouter surface of back-up roll 54. In addition, horn support apparatus 18is configured to retract support rolls 56A, 56B from contact with theouter surface of horn 20, at desirable stages of a bonding operation.

For example, when no active bonding operation is being performed,rotation of horn 20 is typically stopped. To the extent rolls 54, 56A,56B remain in forced engaging contact with horn 20, flat spots developon outer surface 42 of the horn. Such flat spots are expressed insubsequent bond formation in the form of loci of deviation from thedesired consistency of bond development. Such flat spots also tend toimpose stress on ultrasonic horn 20, thereby contributing to wear of thehorn, as well as cracking and failures of horn 20. Therefore, it isdesirable to remove all supporting contact from horn surface 42 at anytime the horn ceases to rotate. Such removal of surface support contactis effected by withdrawing rolls 56A, 56B. from the sides of horn 20,whereupon the weight of the horn causes the horn to sag by gravity, awayfrom, and out of contact with, back-up roll 54.

As representatively illustrated in the drawings, in this invention,ultrasonic horn 20 is mounted above anvil roll 16. Horn support assembly58 is provided to retract support rolls 56A, 56B from contact with outerperipheral bonding surface 42 of horn 20.

As representatively illustrated in FIGS. 1, 2, 4, and 5, horn 20 isconfigured to rotate about horn axis 44 in the direction indicated byarrow 46 associated therewith. Horn 20 can be connected to a shaft 76 bysuitable means such as by using a continuous one-piece design, or studs,or other known means of suitable attachment of a horn to a shaft. Otherrotating components of horn support apparatus 18 can be similarlyconnected to each other as desired, to rotate in common with each other.Horn 20 is accordingly connected to frame 12 through horn supportapparatus 18.

In general, conventional ultrasonic excitation crystals (piezoelectriccrystals) are operationally connected to horn 20 through suitableamplifier and wave guide structure 61, so as to implementradially-directed ultrasonic vibrations in annular horn 20. Amplifierand wave guide structure 61 also functions as a portion of shaft 76supporting the horn. Rotary horn 20 is generally disc-shaped althoughthe precise outer configuration of the horn varies considerably fromhorn to horn in accord with other horn variables.

As representatively illustrated in FIGS. 1, 2, and 4, horn 20 generallycomprises a shaped metal object. Representative examples of rotaryultrasonic horns which can be used in the present invention aredescribed in U.S. Pat. No. 5,096,532 to Neuwirth et al and U.S. Pat. No.5,110,403 to Ehlert, both of which are herein incorporated by referencein their entireties. In general, rotary ultrasonic horn 20 can be madefrom any metal having suitable acoustical and mechanical properties.Suitable metals include aluminum, monel, titanium, and some alloysteels. Titanium is preferred for its overall combination of desirableproperties. In general, variables such as diameter, mass, width,thickness, and configuration of the rotary ultrasonic horn can be variedwithin substantial ranges. However, such variables, along withcomposition of the horn, do determine the particular frequency andamplitude at which a particular rotary ultrasonic horn resonates, whichcan affect bond quality and consistency. In particular, diameter, width,and thickness of the horn are selected such that the horn, upon beingexcited by ultrasonic energy at a desired frequency, is adapted toresonate such that the excited end moves substantially in phase withmovement of the excitation source, and the bonding surface 42 also movesin a suitable pattern which is directed generally perpendicular toannular bonding surface 42 of the horn.

Typically, ultrasonically induced movements of the opposite ends of thehorn relative to each other may be out of phase. For example, the rotaryultrasonic horn illustrated in the drawings can be excited at afrequency of from about 18 kHz to about 60 kHz. Horn 20 typically has adiameter of from about 4 centimeters to about 18 centimeters. Thicknessof the horn at rotational axis 44 is typically from about 0.6centimeters to about 15 centimeters. The horn can have a mass in therange of from about 0.06 kilograms to about 30 kilograms.

Horn support apparatus 18 includes a drive mechanism 60 which rotatesand ultrasonically excites horn 20. Drive mechanism 60 can include theabove noted piezoelectric crystals, the amplifier, and part or all ofthe wave guide. Any mechanism which provides the desired rotation andultrasonic excitation can be used in the present invention. Suchmechanisms are well known to those skilled in the art.

For example, drive mechanism 60 can be a mechanism commerciallyavailable from Dukane Corporation, St. Charles, Ill. or a similar systemavailable from Branson Sonic Power Company, Danbury, Conn. Namely, agenerator such as a Dukane 1800 watt, 20 kHz generator (Part No.20A1800), is connected to a drive assembly, such as a Dukane driveassembly (Part No. 110-3123), to provide the necessary ultrasonicexcitation. Any combination of boosters, such as a Dukane 1:1 booster(Part No. 2177T) and a Dukane 2:1 booster (Part No. 2181T), may then beattached to the drive assembly. Finally, rotary ultrasonic horn 20 ofthe present invention is attached to the boosters. Thus, the combinationof generator, drive assembly, and boosters, functioning as drivemechanisms 60, rotates and ultrasonically excites rotary ultrasonic horn20 thereby providing the ultrasonic energy and rotational motionnecessary to bond workpiece segments 24, 34, or workpiece segment 24 anddiscrete elements, to each other under suitable nip pressure.

Addressing now the support of the horn as illustrated in the drawings,horn 20, along with drive mechanism 60, is generally supported in acantilevered arrangement, on e.g. rubber O-rings 74 (FIG. 5) disposedabout shaft 76. The O-rings support both the horn and the drivemechanism from shaft support structure (not shown). Given the weight ofhorn 20, along with the weight of the drive mechanism, when the weightof the horn and drive mechanism are fully supported by only the O-rings,the weight of the combination of the horn and drive mechanism compressesthe resilient O-rings, whereby the horn sags out of true alignment withthe shaft support structure which supports shaft 76, the horn, and thedrive mechanism. At full sag, and assuming no change in other rollsupport structure positionings, a horn weighing e.g. twenty pounds movesa distance of e.g. about 0.015 inch away from back-up roll 54.

Support rolls 56A, 56B can be spaced around horn 20 in any manner whichsupports horn 20 in a substantially fixed position during bondingoperations, and a position to which horn 20 can be repeatedly returned.Back-up roll 54 preferably engages horn 20 opposite anvil roll 16, thusto provide straight, in-line back-up support to horn 20 through axis 44,whereby horn 20 can be relatively rigidly supported against the upwardforce exerted by anvil roll 16 against horn 20 while avoiding harmfulbending stresses on shaft 76 and compressing forces on O-rings 74,thereby to develop bonding forces in nip 22.

Back-up roll 54, and support rolls 56A, 56B can be made from anysuitable material capable of holding horn 20 in a substantially fixedposition. Exemplary materials for rolls 54, 56A, 56B include metal suchas steel and alloys of other metals, rubber, urethane, and other durablematerials capable of withstanding the pressure and ultrasonic energyenvironments imposed on the respective rolls. In one embodiment, rolls54, 56A, 56B are configured to contact bonding surface 42 of horn 20.Desirably, the support rolls, through frictional engagement with horn20, rotate with the horn to effectively support the horn withoutadversely affecting rotation or ultrasonic vibration of the horn. Rolls56A, 56B can include ball bearings as supports for the rolls, cancomprise bearings per se, or can comprise idler rolls, as are known tothose skilled in the art, configured to contact bonding surface 42 ofhorn 20.

Referring to FIGS. 2 and 4, horn support apparatus 18 comprises a hornsupport plate 78. Support roll guide mechanism 80 includes upstandingfirst and second lever arms 82A, 82B mounted for pivotation with respectto plate 78 at pivot anchors 84A, 84B. Support arms 85A, 85B extend fromlever arms 82A, 82B at pivot anchors 84A, 84B respectively, and move inunison with the respective lever arms, to move rolls 56A, 56B into andout of engagement with outer surface 42 of horn 20. Power cylinder 86extends between lever arms 82A and 82B, and is mounted for pivotationwith respect to lever arms 82A, 82B at pivot pins 88A, 88B, and providesthe motive power moving the lever arms toward and away form each other.Cylinder 86 can be e.g. an air cylinder or an hydraulic cylinder.However, an air cylinder is preferred because of the ability ofcompressed air in the cylinder to absorb, better than hydraulic fluid,shock forces which may be imposed on the system.

Bearing race 90 is rigidly mounted to horn support plate 78 and includesball tracks 92 (FIG. 2). Linear bearing top-mounting plate 94 includes alinear bearing 95 including ball bearings (not shown) which run in balltracks 92, whereby linear bearing top-mounting plate 94 slides up anddown on bearing race 90. Equalizer arm 96A is pivotally mounted to leverarm 82A at pivot pin 98A and is pivotally mounted to linear bearingtop-mounting plate 94 at pivot pin 100A. Equalizer arm 96B is pivotallymounted to lever arm 82B at pivot pin 98B and is pivotally mounted tolinear bearing top-mounting plate 94 at pivot pin 100B. Since linearbearing top-mounting plate 94 can travel only upward and downward onbearing race 90, equalizer arms 96A, 96B, in combination, control themovement of lever arms 82A, 82B such that the lever arms are forced tomove equal distances inward or outward upon activation of power cylinder86. Correspondingly, support arms 85A, 85B are forced to move equaldistances inward or outward, toward or away from horn 20, uponactivation of power cylinder 86. Thus, providing for correspondingset-up, when power cylinder 86 is extended, support arms 85A, 85B movepredictably equal distances toward horn 20, whereby support rolls 56A,56B support ultrasonic horn 20 at a known location in space each timethe support rolls engage the horn.

Since rolls 56A, 56B are below axis 44 of cylindrical horn 20, movementof the support arms inwardly into contact with horn 20 provides alifting vector lifting the horn upwardly. Depending on the distance bywhich the support rolls lift the horn, support arms 85A, 85B canpreferably bring horn surface 42 into surface engagement with back-uproll 54.

Back-up roll 54 is supported by cradle arm 112 connected to horn supportassembly 58. Horn support assembly 58 additionally includes mountingbracket 102 rigidly mounted to support plate 78 at e.g. bolts 104.Spring mounting plate 106 is rigidly mounted to support plate 78 bybolts 108. Similarly, adjustment mounting plate 110 is rigidly mountedto support plate 78. Spring 118 is disposed between cradle arm 112 andspring mounting plate 106.

As illustrated in FIG. 2, horn support assembly 58 includes cradle arm112 and back-up roll 54. Cradle arm 112 includes cradle 113 whichextends on both sides of back-up roll 54. Back-up roll 54 is mounted tocradle 113 between equivalent bearings 114 which are on opposing sidesof roll 54. Using bearings 114 on opposing sides of back-up roll 54,assuming that the axes of rotation of horn 20 and back-up roll 54 aresubstantially aligned, and directing back-up forces through axes 44 and50, urges back-up roll 54 to apply back-up forces in alignment with theaxes of both horn 20 and back-up roll 54, thereby avoiding back-up roll54 applying cantilevered back-up forces. Cradle arm 112 is mounted forpivotation with respect to mounting bracket 102 at pivot pin 116, andextends from mounting bracket 102 to spring mounting plate 106.

Accordingly, when properly set up with the axes of the horn, the back-uproll, and anvil roll 16, substantially aligned with each other, thepressure applied by the outer working surface of back-up roll 54 toouter bonding surface 42 of the horn influences the spacial orientationof the outer bonding surface of the horn to track parallel to outerworking surface 64 of anvil roll 16, such that the outer bonding surfaceof horn 20 can more closely track the incoming and outgoing portions ofpath 36 traversed by workpiece segment 24, with only minimal deviationof bonding surface 42 from the path in accord with pressure applied atnip 22.

Cradle arm 112 is mounted on top of compression spring 118. A load cell120 is disposed above cradle arm 112, at the spring end of the cradlearm. Above load cell 120, adjusting block 122 is rigidly mounted toadjustment mounting plate 110. Adjustment screw 124 extends throughthreaded adjusting block 122 and abuts load cell 120. Adjusting wheel126 is secured to adjusting screw 124. Adjusting wheel 126 turns screw124 and thus effectively raises or lowers the lower end of the adjustingscrew and correspondingly load cell 120, and the corresponding end ofcradle arm 112. Thus, by turning an adjustment device such as adjustingwheel 126, one can pivot the back-up roll with respect to support plate78 at pivot pin 116, thereby raising or lowering back-up wheel 54 withrespect to horn 20.

Spring 118 keeps load cell 120, disposed on cradle arm 112, in contactwith adjusting screw 124 when support rolls 56A, 56B are retracted.Keeping load cell 120 in contact with adjusting screw 124 when supportrolls 56A, 56B are retracted provides a mechanism to ensure that back-uproll 54 does not drop down and establish contact with horn 20, when themachine is stopped, but horn 20 is vibrating. Adjusting block 122 andadjusting screw 124 bear against cradle arm 112 through load cell 120thus to control the positioning of back-up roll 54 against horn 20.Adjusting screw 124 extends through adjusting block 122 and interfaceswith load cell 120 mounted on the top surface of cradle arm 112. Aprogrammable logic controller 119 is connected to the load cell byinformation connection/relay apparatus 121 such as a wire capable ofcarrying signals between the load cell and the programmable logiccontroller. The programmable logic controller connects to servo motor127 through means of information connection/relay apparatus 123 such asa wire capable of carrying signals between the programmable logiccontroller and the adjustor. Load cell 120 emits signals in response toforce applied to load cell 120 from cradle arm 112. The signals fromload cell 120 are conducted by information connection apparatus 121 toprogrammable logic controller 119, wherein the signals are interpreted,and programmable logic controller 119 emits response signals throughinformation connection apparatus 123 to servo motor 127. Adjusting screw124 is adjusted as a result of activating servo motor 127 throughlinking belt 125, to make fine adjustments to the force being exerted byhorn 20 on the anvil roll at nip 22 (FIG. 5) through back-up roll 54,thus to provide fine adjustment of the load being exerted on anvil roll16 at the nip, especially in response to force expressed against theultrasonic horn by raised portion 70 of the anvil roll in the nip (FIG.4).

In general, support roll guide mechanism 80 controls movement of supportrolls 56A, 56B into and out of support of horn 20; and horn supportassembly 58, via cradle arm 112, acting as a closure apparatus in someembodiments, controls the base-line location of back-up roll 54 relativeto horn 20. The use of load cell 120 provides a mechanism to measure thenip force between ultrasonic horn 20 and rotary anvil roll 16.

As representatively illustrated in the drawings, anvil roll 16 isconfigured to rotate about anvil axis 50, and to press substrateworkpiece segment 24, optionally along with a second element orworkpiece segment 34 to be bonded thereto, against bonding surface 42 ofthe ultrasonic horn. The anvil roll is connected to a shaft 62 (FIG. 5)which is rotatably mounted and connected, as part of anvil supportapparatus 14, to frame 12, by any suitable means such as conventionalbearings. In general, anvil roll 16 can be made from any metal havingsuitable mechanical properties for tolerating the use environment, andthe function of urging the materials to be bonded into bondingengagement with surface 42 of the ultrasonic horn. Suitable metalsinclude, for example and without limitation, certain of the alloysteels.

Typically, anvil roll 16 has a width 66 of about 0.6 centimeter to about50 centimeters, desirably from about 0.6 centimeter to about 15centimeters. Operating surface 64 is configured to bond the workpiecesegments 24, 34, or a workplace segment 24 and discrete elements, toeach other at bond locations arranged in a predetermined bond pattern onoperating surface 64. For example, as representatively illustrated inFIG. 6, anvil surface 64 of anvil roll 16 can have an array 67 ofprojections 68 thereon. The array of projections 68 can extendcompletely around the circumference of operating surface 64, and acrossthe entirety of the transverse width of operating surface 64, thereby tocover substantially the entirety of the operating surface of the anvilroll.

In the alternative, projections 68 can be disposed, as shown in FIGS. 3,6, in discrete spaced arrays which cover portions but not all of eitheror both of the circumference or width of the operating surface, of anvilroll 16.

Where an overall pattern is used, the projections suggest continuousbonding force being applied by anvil roll 16 against horn 20. To theextent suitable workpiece segment or other material is in the nipbetween the horn and anvil, the continuous array provides for creating acontinuous bond along the corresponding length of the workpiece segmentover substantially the entirety of the width of the nip.

Breaks in the array of projections, whether partial or full width, canresult in bonds intentionally being developed over less than theentirety of the area of the material passing through the nip. Namely,the extent to which bonds are developed in nip 22, across the width ofthe workpiece segment, depends on the degree to which the array ofprojections 68 or other elements extend across the width of theworkpiece segment. The pattern of projections about the circumference ofthe anvil generally controls the longitudinal arrangement of the bondpattern which can potentially be developed on the materials passingthrough the nip.

Projections 68 can be any size or shape, any orientation ordistribution, depending on the bond pattern desired for the materialpassing through the nip. A preferred, but not limiting bond pattern, isrepresented by about 30 percent bond area and about 70 percent non-bondarea.

In preferred embodiments especially of interest in this invention,surface 64 of anvil roll includes a raised portion 70, also known as a“bump,” illustrated in FIGS. 1, 3, and 4. In such embodiments, the arrayor arrays of projections are disposed on the raise portion or raisedportions. Raised portion 70 is particularly useful when one of workpiecesegments 24, 34, or workpiece segment 24 and discrete elements to bebonded thereto, have varying thicknesses as illustrated in FIG. 6A. Theprinciple of raised portion 70 is to provide a first larger radiusportion of the anvil roll at 70 for providing bonding activity atthinner portions 72 of the workpiece segment, and to provide a secondrelatively smaller radius portion 73 of the anvil roll. The secondsmaller radius portion of the anvil roll provides clearance between theanvil roll and the horn for passage of thicker portions 75 of theworkpiece segment between the anvil roll and the horn. In someembodiments, the first larger radius is about 0.01 inch to about 0.07inch greater than the second smaller radius.

Rotation of the anvil roll can be timed such that raised portion 70 ofanvil roll surface 64 presses thinner portions 72 (FIG. 6A) of workpiecesegments 24, 34 against bonding surface 42 of horn 20 with sufficientforce to develop ultrasonic bonds at thinner portions 72 while thickerportions 75 of the workpiece segment pass through the nip at the smallerradius portions 73 of the anvil roll. Typical of such thicker portionsof the workpiece segment are absorbent pads such as are used indisposable diapers, feminine hygiene pads, and the like.

Such timing of activation of the ultrasonic bonding can be beneficial toestablishing and maintaining desirable levels of interference betweenbonding surface 42 and surface 64 of the anvil roll at the raisedportions, while enabling the thicker portions of the workpiece segmentor other workplace to pass through the nip without being crushed.

When raised portion 70 passes into and through nip 22, the presence ofthe raised portion in combination with the planned interference betweenthe raised portion and the horn, imposes a relatively increased level ofstress on both the horn and the anvil in order to provide suitable forceat the nip to develop ultrasonic bonds using the ultrasonic energy beingexpressed in horn 20. Correspondingly, when raised portion 70 is not inthe nip, namely when a smaller radius portion 73 is in the nip, the nipforce, if any, is substantially less than that required to formultrasonic bonds. Thus, as the anvil and the horn rotate in an ongoingbonding process, raised portion 70 repeatedly passes into and out of thenip, repeatedly stressing both the anvil support structure and the hornstructure, as well as frame 12 onto which are mounted both the anvilsupport structure and the horn support structure.

Each introduction of increased stress includes both passive loading andimpact loading. Particularly the impact loading can introducesignificant variation in effective load along the machine directionlength of the bonding surface defined by raised portion 70, due toreflex reaction of the respective support structures. As a result, bondstrength can vary longitudinally along the length of an array of bondelements represented by the length of raised portion 70, and in someinstances can vary along the width of such array.

For example, when anvil roll 16 is sufficiently loaded against horn 20to develop ultrasonic bonds, as raised portion 70 enters the nip, theimpact of the leading edge of the raised portion meeting the horn causessufficient reactive relative movement of one or both of the horn oranvil roll away from the nip, as a “bounce,” that the effective load inthe nip directly downstream of the leading edge of raised portion 70 isless than the effective load at the leading edge or at the trailing edgeof the raised portion.

Where the dead load applied by the anvil has been set for optimumultrasonic bonding, the reduced load directly downstream of the leadingedge of raised portion 70 results in less than optimum bonding, whiledesired bonding can be achieved elsewhere on the raised portion. If thedead load applied by the anvil is increased such that optimum bonding isachieved directly downstream of the leading edge in spite of the bounce,then optimum bonds may be achieved directly downstream of the leadingedge, while the excessive loading elsewhere on raised portion 70 resultsin inferior bonds and may result in damage to the materials beingbonded.

The force applied by anvil roll 16 at raised portion 70, against horn20, is supported from frame 12 through anvil support apparatus 14.Referring to FIG. 3, anvil support apparatus 14 includes the rotatinganvil roll 16 as an anvil supported adjacent and below path 36 ofworkpiece segment 24. Anvil roll 16 includes outer peripheral workingsurface 64, which includes raised portion 70 and smaller radius portion73. Raised portion 70 contacts workpiece segment 24 and, in combinationwith horn 20, acts upon workpiece segment 24 in nip 22 to developultrasonic bonds while the anvil roll rotates about anvil roll axis 50(FIG. 4) in the direction indicated by arrow 52.

Anvil support apparatus 14 includes anvil loading assembly 128. Anvilloading assembly 128 includes anvil lifting plate 130, anvil loadingpivot plate 132, anvil bottom support plate 134, load transmissionassembly 136, air bladder 138. stop cylinder 140, and longitudinalsupport plate 142.

For purposes of illustration, anvil lifting plate 130 is shown mountedto right side plate 32 of frame 12 in FIG. 1, and slides upwardly anddownwardly with respect to right side plate 32 as indicated by thedouble-headed arrow 144, thereby to provide coarse up and down movementsof the anvil loading assembly with respect to right side plate 32.

In preferred embodiments, anvil lifting plate 130 is mounted to leftside plate 30 such that loading transmission assembly 136 and arms 152A,152B are trailing arms, rather than leading arms, with relationship tothe substrate path indicated by directional arrow 38 (FIG. 1). Atrailing arm relationship of arms 152A, 152B tends to track thesubstrate path more effectively than the leading arm relationshipillustrated between FIGS. 1 and 3. In the illustrated embodiments, allother elements of anvil support apparatus 14 are mounted directly orindirectly to lifting plate 130. Lifting plate 130 is beneficial in thatlifting plate 130 allows for the interchanging of different size anvilsto accommodate the production of different size products. For example,if the anvil is a function roll and makes one revolution per product,the anvil roll circumference and thus anvil roll diameter must change asproduct length changes.

Pivot plate 132 is mounted to lifting plate 130 and pivots about liftingplate 130 at pivot pin shoulder bolt 146. Pivot plate 132 pivots aboutpivot pin shoulder bolt 146 to bring raised portion 70 into a parallelrelationship with bonding surface 42 of horn 20. Spring block 148 ismounted to lifting plate 130. Spring 150 is located and providesrelationship between spring block 148 and pivot block 132. Pivot plate132 is pivoted about pivot pin shoulder bolt 146 by extending andretracting a shaft (not shown), located on the far of side of pivotplate 132, with respect to spring block 148.

Bottom support plate 134 extends outwardly from, and is rigidly mountede.g. by welding or bolting, to lifting plate 130. Support plate 134provides a rigid platform for receiving and supporting air bladder 138,and for receiving and transferring the supported force/load from bladder138 to lifting plate 130 and load transmission assembly 136, thusallowing air bladder 138 to function as a closure apparatus adapted forbringing the anvil roll into contact with the ultrasonic horn withsufficient closure force between the horn and the anvil roll to form aneffective ultrasonic bonding nip.

Load transmission assembly 136 includes first and second load arms 152A,152B mounted to pivot plate 132 at e.g. pivot shaft 154, for cooperativepivotation of arms 152A, 152B about pivot shaft 154, thus to pivot theload transmission assembly about pivot plate 132.

Load transmission assembly 136 further includes transverse brace plate156 which is rigidly mounted to load arms 152A, 152B, and accordinglyconnects, load arms 152A, 152B to each other, such that load arms 152A,152B, and brace plate 156 move and otherwise act in unison as a unitarybody.

Load transmission assembly 136 further includes cross tube 158 whichextends between and is rigidly mounted to load arms 152A, 152B, and isalso rigidly mounted to brace plate 156, so as to coact with load arms152A, 152B, and brace plate 156. Further, bottom plate 160 is rigidlyattached to brace plate 156 and to load arm 152B at bottom edges of therespective load arm and brace plate. Bottom plate 160 serves as aninterface between the load transmission assembly and air bladder 138.

Load transmission assembly 136 also includes the above discussed anvilroll 16, including raised portion 70 and smaller radius portion 73. Theanvil roll is mounted through anvil shaft 62 to load arms 152A, 152B,preferably through bearings (not shown) at each of the load arms. Anvilshaft 62 extends through cross tube 158 between load arms 152A, 152B.Shaft 62 is visible outside the outer surface of load arm 152A. Asillustrated in FIG. 3A, shaft 62 is connected to and rotates with drivegear 162, harmonic phasing unit 162A, and drive gear 161, drive gear 161being hidden behind drive gear 162 in FIG. 3, but shown in FIG. 3A.Accordingly, anvil 16 rotates in unison with drive gears 161, and 162,and, due to the affect of harmonic phase adjuster 162A, drive gear 162can precess relative to anvil 16. Harmonic phase adjuster 162A can be,for example, an Infinit-Indexer® Phase Adjuster commercially availablefrom Harmonic Drive® of Quincy Technologies, Inc., Wakefield,Massachusetts, or any other functionally similar mechanism.

Drive gear 163 is connected to drive pulley 163A and driven by timingbelt 169 which is connected to input drive pulley 167. Gear 163 drivesgear 161, which is shown disposed behind gear 162 in FIG. 3A. Drive gear161 interacts via meshing teeth 165 with drive gear 163 to rotate anvilroll 16. Harmonic phasing unit 162A is keyed to shaft 62, and, inaddition, is affixed to gear 162. Gear 162 connects to, and drives, agear (not shown) which is connected to the horn assembly, whereby anvilroll 16 and horn 20 rotate cooperatively in combination with the passageof workpiece segment 24 et al through nip 22. The use of harmonic phaseadjuster 162A enables the rotation of the horn to not be rigidly gearedto the rotation of the anvil roll, but enables the horn to driftslightly such that the pattern of the pins on the anvil roll does notride on and, thusly, wear grooves in the same respective locations ofthe horn.

The primary lifting force on anvil roll 16 is transmitted from liftingplate 130 through bottom support plate 134, through bladder 138, throughload transmission assembly 136, and thence to anvil roll 16. Bladder 138also serves as a shock absorber to receive and dissipate load shocks,e.g. impact load shocks, imposed on the load transmission assemblythrough anvil 16, especially at raised portion 70. In preferredembodiments, bladder 1 38 applies a lifting load of about 300 pounds onload cell 176. The respective e.g. 300 pound load registers at facevalue at load cell 176. To the extent some or all of the respective loadis transferred to horn 20 through anvil 16, the load registering on loadcell 176 is correspondingly reduced. Correspondingly, any loadtransferred from anvil roll 16 to horn 20 is registered as an additionalload increment at load cell 120. Thus either load cell can be used tomonitor and ultimately control the force in the nip 22 betweenultrasonic horn 20 and the rotary anvil roll 16.

The amount of lifting force applied by bladder 138 should be sufficientto provide relative stability to anvil roll 16, while enabling the anvilroll to move away from the nip in the event an excess load is generatedat the nip.

Longitudinal support plate 142 is rigidly mounted e.g. by welding orbolting to lifting plate 130. Support plate 142 serves as a stabilizingelement and as a link between side plates 30, 32 of frame 12. In thatregard, lifting plate 130 is rigidly mounted to side plate 32 (FIG. 1),and a bolt (not shown) extends through slot 164 of the support plate andsecures support plate 142 to side plate 30. Such securement to sideplate 30 is loosened for sliding lifting plate 130 upwardly ordownwardly, depending on the size of the anvil, with respect to sideplates 30, 32, and is then tightened to hold the support plate rigidlyto side plate 30 at the selected elevation during routine use of thebonding apparatus.

Stop cylinder support bracket 166 is rigidly mounted to support plate142 as by welding or bolting, and rigidly supports stop cylinder 140.Cylinder 140 includes extension rod end block 168 which extends toward,and is in alignment with, lower surface 170 of load arm 152B. Rod endblock 168 can be extended or retracted to establish the lowest enabledpoint of travel of load transmission assembly 136 as lifting plate 130is moved downwardly to lower anvil roll 16 away from horn 20. Byestablishing the lower limit of travel of load transmission assembly 136at a height wherein gear 162 and the gear (not shown) driving the hornremain engaged. Disengagement of the anvil roll from the horn does notdisengage the lower drive gears from the upper drive gears.

During routine operation of the bonding process, rod end block 168 isdisplaced somewhat downwardly from lower surface 170 of load arm 152B.Rod end block 168 can be raised or lowered routinely to adjust thedesired lowest height of load arm 152B, and thus the lowest height ofload transmission assembly 136 with respect to lifting plate 130.

Support bracket 172 is mounted to the top surface of longitudinalsupport plate 142. Adjusting screw 174 extends through support bracket172 and interfaces with a load cell 176 mounted on the top surface ofload arm 152B. A programmable logic controller 171 is connected to theload cell by information connection/relay apparatus 177 such as a wirecapable of carrying signals between the load cell and the programmablelogic controller. The programmable logic controller connects to servomotor 178 by information connection/relay apparatus 179 such as a wirecapable of carrying signals between programmable logic controller 171and servo motor 178. Load cell 176 emits signals in response to forcesapplied to load cell 176 by load arm 152B. The signals from load cell176 are conducted by information connection apparatus 177 toprogrammable logic controller 171, wherein the signals are interpreted,and programmable logic controller 171 emits response signals throughinformation connection apparatus 179 to servo motor 178. Adjusting screw174 is adjusted as a result of activating servo motor 178 throughlinking chain 180, to make fine adjustments to the force being exertedby anvil roll 16 on horn 20, thus to provide fine adjustment of the loadbeing exerted on horn 20 by especially raised portion 70 of the anvilroll.

The present invention addresses the problem of consistency of the loador force/pressure being exerted on the workpiece segment by the horn andthe anvil at nip 22 when the raised portion of the anvil is in nip 22.First, support surfaces 54, 56A, 56B are provided for fixing theposition of the horn with respect to frame 12 during the bondingoperation, and wherein any cantilever elements of the force vectors arecanceled by opposing force vectors, whereby cantilever vectors havelittle or no effect on positioning of horn 20. Second, the collectiverigidity, stiffness, of bonding apparatus 10 is increased in order toreduce the amount of interference, between horn 20 and anvil roll 16,which is required in order to achieve the needed nip load toultrasonically generate bonds having satisfactory bond strength.

The compositions of workpiece segments 24 and/or 34 can be any materialsknown to those skilled in the art which are compatible with developmentof ultrasonic bonds.

For example, workpiece segments 24, 34 can include one or more nonwovenmaterials such as spunbond, melt blown, spun laced or carded polymericmaterials, a film material such as a polyolefin, for examplepolyethylenes and/or polypropylenes, or a polyurethane film, a foammaterial, or combinations of the above recited materials.

For purposes of the present description, “nonwoven workpiece segment”means a fibrous web of material which is formed of fibers without aid ofa textile weaving or knitting process. Workpiece segments 24, 34 may beelastic or non-elastic such as films or layers of natural rubber,synthetic rubber or thermoplastic elastomeric polymers.

Typical workpiece segments bonded using the invention have thicknessesof about 0.0005 inch to about 0.25 inch at bonding loci, and may havegreater or lesser thicknesses at loci of the workpiece segment which arenot being so bonded.

As used herein, the terms “elastomeric” or “elastic” refer to anymaterial which can be elongated or stretched in a specified directionfrom about 20 percent to at least about 400 percent by application of abiasing force and which recovers to within about 35 percent of itsoriginal length after being subsequently released from the biasing forceafter a short-term duration of the stretched condition.

Workpiece segments 24, 34 can be made from a common material or can bemade from different materials. In some embodiments, at least one of theworkpiece segments is made from resiliently stretchable material such asstretch-bonded-laminate (SBL) material, neck-bonded laminate (NBL)material, elastomeric film, elastomeric foam, or like resilientlystretchable materials as are well known to those skilled in the art.

The bonding resulting from application of ultrasonic energy can resultfrom partial or complete melting of materials in one or both ofworkpiece segments 24 or 34, or partial or complete melting of materialin a corresponding element being applied to a respective workpiecesegment. Bonding can result from partial or complete melting of materialof only one of the elements being acted upon, with the activatedmaterial interacting with the corresponding adjacent workpiece segmentor element which in turn results in mechanical interlocking of theelements/workpiece segments to each other.

In the alternative, bonding can result in mutual partial or completemelting of materials of both the elements being acted upon, with flowand/or other interaction between or among the respective materials ofboth elements which results in a bonding better represented as adhesivebonding or cohesive bonding, optionally in combination with theabove-recited mechanical interlocking of components of one or both ofthe respective elements to each other.

In some embodiments of the invention, portions of continuously movingworkpiece segments 24, 34 are both softened and/or melted usingultrasonic energy supplied to the rotary ultrasonic horn, along withsufficient pressure to activate the materials in the respectiveworkpiece segments, whereby the workpiece segments are thus bonded toeach other through simultaneous application of ultrasonic energy andpressure. In such a configuration, anvil roll 16 is configured to rotateabout anvil axis 50 and to press workpiece segments 24, 34 against theouter peripheral bonding surface of ultrasonic horn 20 e.g. at raisedportion 70 thereby bonding the workpiece segments to each other. Asillustrated in FIGS. 2, 4, and 5, support rolls 56A, 56B are configuredto contact outer bonding surface 42 of horn 20 to hold horn 20 in asubstantially fixed location while the support rolls are engaginglysupporting horn 20.

When ultrasonic vibration of a rotary ultrasonic horn is commenced, theenergy passing through the horn causes the temperature of the horn torise. As the temperature of the horn rises, the size, including thediameter, of the horn changes. As the diameter of the horn changes, theinferred interference changes, as does the corresponding nip pressure,and the resonant frequency. As the nip pressure changes, bond qualitychanges. In order to avoid the above changes of processing parameters,it is common to leave the horn energized, though not rotating, even whenthe horn is not being used, so that the operator need not deal with sizechanges as a process variable.

With the horn energized but not rotating, any substantial objectdisposed against outer working surface 42 of the stationary horn cancause development of a flat spot on the horn surface at the locus oftouching. Accordingly, it is important that all support of horn 20 atsurface 42 be withdrawn when the horn is not rotating. Such withdrawalof horn support has both operational and structural implications.Operationally, the programmable logic computer (not shown) whichcontrols operation of the system, is programmed to automaticallywithdraw support rolls 56A, 56B from surface 42 any time rotation ofhorn 20 is stopped. Structurally, horn 20 is intentionally positionedbelow back-up roll 54 such that, when rolls 56A, 56B are withdrawn, theweight of horn 20 causes the horn to sag away from back-up roll 54,along with corresponding compression of O-rings 74. For an exemplaryhorn approximately 6 inches diameter, three inches thick, the horntypically sags about 0.010 inch to about 0.025 inch away from back-uproll 54.

Withdrawing support rolls 56A, 56B causes ultrasonic horn 20 to sag andcome out of contact with back-up roll 54 e.g. at the end of a bondingproject, and re-engaging support rolls 56A, 56B, lifting ultrasonic horn20 into contact with the back-up roll at initiation of a subsequentproject, returns the ultrasonic horn to the same defined location. Thedisengagement of support rolls 56A, 56B and subsequent resultant saggingof ultrasonic horn 20 away from back-up roll 54 allows the horn tocontinue vibrating with other portions of the machine stopped. Thecontinued vibration of the horn keeps the diameter of the ultrasonichorn constant, since ultrasonic horns tend to demonstrate thermalexpansion during operation.

Referring now to FIG. 7, the actual touching contact is illustrated insolid outline while the dashed outline of anvil roll 16 illustrates theposition that would be occupied by anvil roll 16 in the absence of theinterference with horn 20. Thus the dashed outline illustrates theamount of interference inferred by the settings of e.g. adjusting wheel126 and/or adjusting screw 174.

As used herein, “interference” is measured by first fixing the horn inits bonding position, with support rolls 56A, 56B supporting horn 20against back-up roll 54, with the sag removed from the horn. Preferablyadjusting screw 124 and/or adjusting screw 174 are calibrated such thateach revolution of the respective screw represents a known distance ofadvance of the respective horn or anvil roll. Such advance must, ofcourse, take into account the lever arm between the respective screw,the point of pivotation, and the point of application of force byback-up roll 54. Thus, where the screw represents a second class leverapplying force between the screw and the pivot point as in theillustrated embodiments, the distance traveled by the screw end of thelever arm will be greater than the distance traveled by the back-up roll54. Respectively, the distances recited herein for advance of theback-up roll are distances effective at the back-up roll, though suchdistances may be determined based on measurements or calibrationsdetermined at the adjusting screw.

In the illustrated embodiments wherein force is applied on the back-uproll through a second class lever, the lever arm is an element in thestiffness analysis. In embodiments wherein the force on the back-up rollis applied to cradle arm 112 in line with the axes of the back-up rolland the horn, there is no lever arm requiring bending stiffnessanalysis. In either analysis, bladder 138 provides relief for anyoverstressing condition at the nip, since the forces in excess of thatbeing exerted by the bladder cause the bladder to move downwardly, thuswidening the actual physical gap at the nip. In a like manner, stopcylinder 140 also accommodates deflection of load transmission assembly136 in response to stress in the nip.

In conventional processes at least 0.009 inch of interference, typicallygreater than 0.010 inch, is required to achieve satisfactory force inthe nip to obtain bonding with ultrasonic energy. Use of lessinterference in a conventional environment does not provide sufficientforce in the nip to develop sufficiently high strength ultrasonic bonds.However, as noted earlier, the levels of interference conventionallyused for continuous bonds, when used in an intermittent bonding process,are accompanied by the recited bounce, and the related inconsistency ofbonding developed as a result.

In order for the horn and anvil to exert sufficient pressure at bondingnip 22, the horn and/or anvil must move toward each other to close andpressurize the nip. Description of the process starts with the horn andanvil spaced from each other, with the horn in dead load free sag withno support being applied directly to surface 42. 400 pounds of force isbeing exerted by bladder 138 against load cell 176. Back-up roll 54 isbrought to a distance from the horn surface which represents the sagdistance. Where, for example, the sag distance is 0.015 inch, roll ispositioned 0.015 inch above the top of horn 20. Then support rolls 56A,56B are brought into supporting contact with the sides of horn 20, androlls 56A, 56B are further driven to lift the horn into contact withback-up roll 54. With support rolls 56A, 56B holding the horn againstback-up roll 54. the horn is then held fixed by rolls 54, 56A, 56Bcollectively in its operating position. All that remains is to apply theinterference pressure required to activate bonding responses to theultrasonic energy passing through horn 20. To that end, adjusting screw174 of the anvil support apparatus is turned the desired amount to applythe amount of “interference” force required to activate a bondingresponse in the workpiece segment and/or other workpieces being bonded.Typically, a force of about 400 pounds per inch width of the nip issufficient to produce an acceptable ultrasonic bond in nip 22 whilepreserving the integrity of a typical non-woven workpiece segment usedin fabricating absorbent articles such as diapers.

FIG. 8 illustrates a curve showing raw data readings as well as a linerepresenting generally normalized readings of stop force at the loadcell at various points in the rotation of the anvil roll at the nip.Generally, nip loads of 400 pounds per inch up to greater than about1000 pounds per inch of nip width are needed to produce the desiredbonds in material currently used in fabricating absorbent articles. Theillustrated anvil support apparatus (FIG. 3) uses air bladder 138 toraise and hold anvil arm 152B against a fixed stop (load cell) 176. Theamount of loading at the nip is controlled by adjusting the air pressureto the loading device (air bladder) 138, and inuring adjusting screw174. For example, approximately 60 PSIG air pressure in the air bladderproduces 150 pounds of force at the load cell (baseline of FIG. 8) or375 pounds available at the anvil/horn nip. If, for illustrativepurposes, the anvil pattern is about 0.25 inch wide, the resultantpressure in the nip would be a maximum load of 1500 pounds per inch (375pounds/0.25 inch) nip width. Experimental data shows that there is arange of acceptable loads and horn amplitudes, but a typical value isthat 0.003 inch of interference in the illustrated bonding apparatus 10,and using 60 PSIG air, produces an 80 pound reading at the load cell,with the balance of 70 pounds of load cell-equivalent force (150pounds−80 pounds 70 pounds) being expressed at the nip. Such load cellforce of 70 pounds equates to 175 pounds of force at the anvil(375/150×70), or 700 pounds per inch, assuming a 0.25 inch wide nip,(175 pounds/0.25 inch) nip width. A preferred alternative is to tare theinitial load cell reading and display the change in load, when the anviland horn are brought together to form a nip, as a positive number. Thereading from the load cell can also be scaled to account for the leverarm between the load cell and the nip, thus to have the load celldisplay directly the load at the nip. The nip load can be divided by thenip width e.g. by the load cell to provide a resulting value of the nipload per inch nip width.

If back-up roll 54 is adjusted to account for a respective amount ofhorn sag, for example, generally being approximately 0.015 inch, above aportion of the unloaded horn surface 42 closest to back-up roll 54,substantially all the force distributed to O-rings 74 closest to thehorn face due to the weight of the horn is removed, when the horn islifted. Similarly, as first and second support rolls (56A, 56B) areurged inwardly against outer surface 42 of ultrasonic horn 20 thuslifting the horn upwardly against back-up roll 54, if the back-up rollis set to account for the respective amount of horn sag, as statedabove, the lifting of the horn by support rolls 56A, 56B takes the loadoff O-rings-74 disposed closest to the horn face.

FIG. 9 illustrates a curve showing raw data readings as well as a linerepresenting generally normalized readings, of stop force between thehorn and back-up roll at various points in their common rotation. Theillustrated cradle arm 112, through back-up roll 54, of horn supportapparatus 18 (FIGS. 2, 4) is held against load cell 120 by forces ofboth the anvil forcing the horn upward, and the support wheels 56A, 56Burging the horn in an upward direction. The amount of loading on back-uproll 54 is controlled by the closed loop control apparatus comprisingload cell 120. programmable logic controller 119, and servo motor 127.Referring to FIG. 9, approximately 140 pounds of force at the load cell(baseline of FIG. 9) creates a sufficient amount of force to off-setupward forces created at the anvil/horn nip.

In the above scenario, the provision of back-up roll 54 eliminates or atleast attenuates overhung load on shaft 76, whereby developing bondingforce in the nip relies more on the stiffness and rigidity of hornsupport apparatus 18 than on the stiffness of shaft 76 and 0-ringsupports. The pressure in bladder 138 provides the desired force to holdload transmission assembly 136 against adjusting screw 174.

In some embodiments, the output of the load cell in either the anvilloading assembly, or at the cradle arm of the back-up roll is first fedinto a strain gauge isolated transmitter. The signal is then fed into aprogrammable logic controller having software capable of interpretingthe signal, e.g. Rockwell Software RSLogix 5. If the signal average isat the setpoint of the load cell, the servo motor remains inactivated.If the signal average falls outside a threshold variance of e.g. about±10 pounds, the controller program causes an adjustment device, e.g.servo motor, to adjust the stop position. The value of the thresholdvariance can, of course, be set at any value desired, greater than orless than 10 pounds, for a particular use contemplated for the bondingapparatus. As a further option, the output of load cell 120 can be usedto control servo motor 178 and/or the output of load cell 176 can beused to control servo motor 127.

As indicated above, the force developed in nip 22 passes through avariety of elements to get back to frame 12. Accordingly, the criticalstructural consideration is the overall stiffness of the framedstructure 10. Such stiffness can be achieved in various ways withvarious specifications for the respective elements of the structure. Theimportant parameter is that the required interference level achieves asuitable force at nip 22 to develop ultrasonic bonds in the workpiece.

For example, strengthening. stiffening only the frame members (e.g. 26,28, 30, 32) while not addressing members of anvil support apparatus 14or horn support apparatus 18 can leave excess deflection in supportapparatus 14 and/or 18. Correspondingly, stiffening support apparatus14, 18 while not addressing the frame members can similarly leave excessdeflection in the frame. Thus, whatever the starting structure not ofthis invention, the objective of achieving suitable stiffness ismeasured as the resulting amount of interference required to achievegood quality ultrasonic bonds. By thus expressing the invention in termsof the resulting interference, one can achieve the invention while beingfree to choose and design various elements, subassemblies, andassemblies while also freely selecting desired materials ofconstruction, suitable to the user's specific application.

Those skilled in the art will now see that certain modifications can bemade to the apparatus and methods herein disclosed with respect to theillustrated embodiments, without departing from the spirit of theinstant invention. And while the invention has been described above withrespect to the preferred embodiments, it will be understood that theinvention is adapted to numerous rearrangements, modifications, andalterations, and all such arrangements, modifications, and alterationsare intended to be within the scope of the appended claims.

To the extent the following claims use means plus function language, itis not meant to include there, or in the instant specification, anythingnot structurally equivalent to what is shown in the embodimentsdisclosed in the specification.

Having thus described the invention, what is claimed is:
 1. Ultrasonicbonding apparatus for creating ultrasonic bonds in sequentiallyadvancing workpiece segments, in a nip defined by a rotary ultrasonichorn mounted for rotation about a first axis, and a rotary anvil rollmounted for rotation about a second axis substantially aligned with thefirst axis, said anvil roll comprising a width, a circumference, and abonding portion disposed about at least a portion of the circumference,said ultrasonic bonding apparatus comprising: (a) support structurecomprising anvil support apparatus connected to said anvil roll, andhorn support apparatus connected to said ultrasonic horn, said supportstructure supporting said bonding apparatus from a support; (b) saidanvil support apparatus comprising an anvil moving assembly for movingsaid anvil roll into contact with said ultrasonic horn, and for movingsaid anvil roll out of contact with said ultrasonic horn; (c) closedloop control apparatus connected to one of said anvil support apparatusand said horn support apparatus, said closed loop control apparatuscomprising a programmable logic controller, a load cell, and anadjustor, said ultrasonic horn and said anvil roll collectively beingmounted and configured such that said ultrasonic horn and said anvilroll can be brought together to define the nip therebetween, and whereinsaid anvil roll and said ultrasonic horn can rotate in common withmovement of workpiece segments through the nip, information output fromsaid load cell triggering said closed loop control apparatus throughsaid programmable logic computer and said adjustor to move said one ofsaid anvil support apparatus and said horn support apparatus toward andaway from the other of said anvil support apparatus and said hornsupport apparatus in automatic and dynamic response to the informationoutput from said load cell, and thereby regulating pressure in the nipwith ongoing real-time adjustments to distance between said anvilsupport apparatus and said horn support apparatus.
 2. Ultrasonic bondingapparatus as in claim 1, said load cell being arranged and configured tomeasure representative nip loads, thereby to define forces generatedbetween said ultrasonic horn and said anvil roll.
 3. Ultrasonic bondingapparatus as in claim 1 wherein said adjustor comprises a servo motor.4. Ultrasonic bonding apparatus as in claim 1, comprising a load cellconditioner connected to said load cell, said load cell conditioneramplifying output from said load cell.
 5. Ultrasonic bonding apparatusas in claim 1, including a back-up roll juxtaposed adjacent saidultrasonic horn, opposite said anvil roll , and wherein said back-uproll engages an outer surface of said ultrasonic horn at an engagementlocus in alignment with a line extending through extensions of the firstand second axes.
 6. Ultrasonic bonding apparatus as in claim 5,including a second adjustor mounted and configured for adjusting aheight of said back-up roll, and thus generally defining a limit tomovement of said ultrasonic horn away from said anvil roll. 7.Ultrasonic bonding apparatus as in claim 1 wherein said closed loopcontrol apparatus is connected to said horn support apparatus. 8.Ultrasonic bonding apparatus as in claim 1 wherein said closed loopcontrol apparatus is connected to said anvil support apparatus. 9.Ultrasonic bonding apparatus as in claim 1, said anvil moving assemblydefining a limit to travel of said anvil support apparatus away fromsaid horn support apparatus, thus defining a limitation to withdrawal ofsaid anvil roll from the nip.
 10. Ultrasonic bonding apparatus as inclaim 1, including first and second support rolls releasably supportingopposing sides of an outer surface of said ultrasonic horn. 11.Ultrasonic bonding apparatus as in claim 10 wherein axes of said firstand second support rolls are positioned lower than the axis of theultrasonic horn, whereby urging said first and second support rollsinwardly against the outer surface of said ultrasonic horn lifts saidultrasonic horn upwardly against said back-up roll.
 12. Ultrasonicbonding apparatus as in claim 1, including drawing apparatus, capable ofdrawing the workpiece segments through said bonding apparatus, acrosssaid anvil roll, and thus through the nip defined between said anvilroll and said ultrasonic horn, at a threading speed of at least about 40feet per minute.
 13. Ultrasonic bonding apparatus as in claim 1,including drawing apparatus, capable of drawing the workpiece segmentsthrough said bonding apparatus, across said anvil roll, and thus throughthe nip defined between said anvil roll and said ultrasonic horn, at aspeed of at least about 600 feet per minute.
 14. Ultrasonic bondingapparatus as in claim 1, said support structure being sufficiently rigidthat said ultrasonic horn and said anvil roll can be brought togetherwith deflection levels of said horn support apparatus and said anvilsupport apparatus, in combination, being no more than about 0.003 inchin combination with defining sufficient nip pressure to developultrasonic bonds in the workpiece segments passing through the nip. 15.Closed loop control apparatus for managing pressure generated in a nip,the nip being defined between a rotary ultrasonic horn mounted forrotation about a first axis, and an anvil roll mounted for rotationabout a second axis, substantially aligned with the first axis, andwherein the anvil roll is mounted to support structure by anvil supportapparatus, and the ultrasonic horn is mounted to the support structureby horn support apparatus, said closed loop control apparatuscomprising: (a) an adjustor mounted in adjusting relationship withrespective one of the anvil support apparatus and the horn supportapparatus; (b) a load cell connected to one of the anvil supportapparatus and the horn support apparatus, said load cell quantifyingforce representative of pressure being generated in the nip; and (c) aprogrammable logic controller connected to said load cell and to saidadjustor, for communication with said load cell and said adjustor. 16.Closed loop control apparatus as in claim 15, said closed loop controlapparatus further comprising a strain gauge isolated transmitterconverting force applied on said load cell into signal output. 17.Closed loop control apparatus as in claim 16 wherein said load celltransmits the signal output to said programmable logic controller. 18.Closed loop control apparatus as in claim 15 wherein said anvil supportapparatus can be raised or lowered by said adjustor in response tooutput of said load cell and said programmable logic controller untilforce applied to said anvil support apparatus results in desiredultrasonic bond-creating pressure in the nip.
 19. Closed loop controlapparatus as in claim 15 wherein said horn support apparatus has a firstend portion mounted to said support structure, and a second end portionremote from the first end portion, and disposed on a horn movingassembly.
 20. Closed loop control apparatus as in claim 19, said closedloop control apparatus being operatively connected to said anvil supportapparatus, a second closed loop control apparatus being connected tosaid horn moving assembly, thereby providing a second control formanaging pressure in the nip, said second closed loop control apparatuscomprising a second adjustor mounted in adjusting relationship with saidhorn moving assembly, and a second load cell connected to one of thehorn moving assembly and said second adjustor and outputting informationto a suitable programmable logic controller.
 21. A method of creatingultrasonic bonds in sequentially advancing workpiece segments, themethod comprising: (a) passing the workpiece segments through a nipdefined by a support structure comprising anvil support apparatussupporting an anvil roll mounted for rotation about a first axis, hornsupport apparatus being connected to and supporting a rotary ultrasonichorn mounted for rotation about a second axis, substantially alignedwith the first axis, the anvil support apparatus comprising an anvilmoving assembly for moving the anvil roll into contact with theultrasonic horn, and for moving the anvil roll out of contact with theultrasonic horn, closed loop control apparatus being connected to one ofthe anvil support apparatus and the horn support apparatus, the closedloop control apparatus comprising a programmable logic controller, aload cell, and an adjustor; (b) activating ultrasonic energy in theultrasonic horn; and (c) rotating the ultrasonic horn and the anvil rollin common with movement of the workpiece segments through the nip,thereby applying pressure to the workpiece segments at the nip, andcorrespondingly creating ultrasonic bonds in the workpiece segmentspassing through the nip, the programmable logic controller beingconnected to the load cell and the adjustor, and communicating with theload cell and the adjustor, and regulating pressure in the nip byongoing real-time adjustments to the distance between the anvil supportapparatus and the horn support apparatus.
 22. A method as in claim 21,including sensing nip loads using the load cell, the nip loadsrepresenting forces expressed between the ultrasonic horn and the anvilroll at the nip.
 23. A method as in claim 21, the nip having a widthdefined between the ultrasonic horn and the anvil roll, includingemploying the horn support apparatus and the anvil support apparatus,collectively, thereby to define a set-point target nip pressure of atleast about 400 pounds per inch width of the nip.
 24. A method as inclaim 23 including initiating adjustment to the anvil moving assemblywhen nip load deviates from a target nip load by at least about 10pounds per inch width of the nip.
 25. A method as in claim 23, includingadjusting the anvil moving assembly when loading in the nipcorresponding to a bonding portion of the anvil roll varies by more thanabout 10 pounds per inch width of the nip from the target nip loading.26. A method as in claim 21, including connecting a load cellconditioner to the load cell, and thereby amplifying output from theload cell.
 27. A method as in claim 21, including connecting the closedloop control apparatus to one of the horn support apparatus and theanvil support apparatus.
 28. A method as in claim 27, including managingpressure in the nip by employing the closed loop control apparatus as afirst closed loop control apparatus connected to the anvil supportapparatus, and employing second closed loop control apparatus connectedto the horn support apparatus, at least one of the first and secondclosed loop control apparatus comprising an adjustor mounted inadjusting relationship with the respective support apparatus, and a loadcell connected to at least one of the horn support apparatus and theanvil support apparatus, and the respective adjustor.
 29. A method as inclaim 21, including processing information output from the load cell inthe programmable logic controller and correspondingly raising andlowering one or both of the anvil support apparatus or the horn supportapparatus, thereby regulating the pressure in the nip.
 30. A method asin claim 21, including applying first and second support rolls to sidesof the ultrasonic horn and moving the ultrasonic horn into engagementwith a back-up roll aligned with extensions of the first and second axessuch that the first and second support rolls, in combination with theback-up roll, define a fixed location of operation of the ultrasonichorn.
 31. A method as in claim 21 wherein the bringing of the anvil rolland the ultrasonic horn together comprises lifting the anvil roll,thereby to bring the anvil roll into engaging relationship with theultrasonic horn.
 32. A method as in claim 21, including limitingdownward movement of the anvil moving assembly and thereby preventingdisengagement of drive apparatus which transmits drive power between theanvil support apparatus and the horn support apparatus.
 33. A method asin claim 30, including adjusting height of the back-up roll and therebycontrolling the location of operation of the ultrasonic horn.
 34. Amethod as in claim 30, including releasing the support rolls, causingthe horn to drop out of engagement with the back-up roll, andsubsequently re-engaging the support rolls with the ultrasonic horn, andthus bringing the ultrasonic horn back into engagement with the back-uproll, and thereby returning the ultrasonic horn to the defined locationof operation of the ultrasonic horn.
 35. A method as in claim 21,including using the load cell to measure, and to dynamically manage, niploads expressed in the nip, in real time.
 36. A method of managingpressure generated in a nip, the nip being defined between a rotaryultrasonic horn mounted on horn support apparatus, and an anvil rollmounted on anvil support apparatus, the anvil support apparatus beingmounted to a support structure, and defining an adjustable anvil movingassembly, the horn being mounted in general alignment with the anvilroll to define the nip therebetween such that outer working surfaces ofthe ultrasonic horn and the anvil roll are generally defined in a commonsurface at the nip, the method comprising: (a) employing a load cellconnected to one of the horn support apparatus and the anvil supportapparatus, and thereby receiving and quantifying force representative offorce expressed between the ultrasonic horn and the anvil roll at thenip; (b) converting the force applied at the load cell into acommunications signal output; (c) transmitting the communications signaloutput to a programmable logic controller programmed to activate anadjustor; and (d) employing the adjustor to raise or lower therespective anvil support apparatus or horn support apparatus so as toadjust the force being expressed between the anvil roll and the horn atthe nip to a desired bond-creating pressure.
 37. A method as in claim36, including employing a target nip pressure of at least about 400pounds per inch width of the nip.
 38. A method as in claim 37, includingadjusting location of the respective anvil support apparatus or hornsupport apparatus when pressure in the nip corresponding to a bondingportion of the anvil roll deviates from the target nip pressure by adefined number of pounds per inch width of the nip.
 39. A method as inclaim 38, the defined number of pounds being about 10 pounds per inchwidth of the nip.
 40. A method as in claim 36, including the hornsupport apparatus having a first end portion fixed to the supportstructure, and a second end portion remote from the first end portion,disposed on a horn moving assembly, the method including at least inpart managing pressure in the nip by connecting closed loop controlapparatus to the horn moving assembly.